Fabrication procedure of non-binder bio-based carbon electrode for battery and supercapacitor

Abstract

A method for forming a carbon electrode can include forming a blank comprising a bio-based material, constraining the blank, pyrolyzing the blank, and forming a carbon electrode based on pyrolyzing the blank. The method can also include activating the carbon electrode during the formation of the carbon electrode or thereafter. The bio-based material can include wood, coconut shell, bamboo, rice husks, hemp, jute, or any combination thereof.

1 . A method for forming a carbon electrode, the method comprising:
 forming a blank comprising a bio-based material;   constraining the blank;   pyrolyzing the blank; and   forming a carbon electrode based on pyrolyzing the blank.   
     
     
         2 . The method of  claim 1 , wherein forming the blank comprises:
 cutting a flat block of the bio-based material to form the blank, wherein the flat block is cut in a radial and longitudinal direction.   
     
     
         3 . The method of  claim 1 , wherein the blank has a thickness between about 0.3 mm and about 0.8 mm. 
     
     
         4 . The method of  claim 1 , wherein the bio-based material comprises wood, coconut shell, bamboo, rice husks, hemp, jute, or any combination thereof. 
     
     
         5 . The method of  claim 1 , wherein forming the blank comprises:
 retting biomass;   extracting natural fibers from the biomass based on the retting; and   forming the blank from the natural fibers.   
     
     
         6 . The method of  claim 1 , wherein constraining the sheet comprises:
 placing a mechanical constraint on top of the blank during the pyrolyzing.   
     
     
         7 . The method of  claim 6 , wherein the mechanical constraint comprises a porous material, a mesh, a screen, or any combination thereof. 
     
     
         8 . The method of  claim 6 , wherein the mechanical constraint has a melting point above a pyrolysis temperature of the sheet. 
     
     
         9 . The method of  claim 1 , wherein pyrolyzing the blank occurs at a temperature between about 600° C. and about 1,000° C. 
     
     
         10 . The method of  claim 1 , wherein pyrolyzing the blank occurs under a vacuum pressure. 
     
     
         11 . The method of  claim 1 , further comprising:
 treating the blank with an activation agent prior to pyrolyzing the blank.   
     
     
         12 . The method of  claim 1 , further comprising:
 treating the carbon electrode with an activation agent.   
     
     
         13 . The method of  11 , wherein the activation agent comprises at least one of KOH, ZnCl 2 , H 3 PO 4 , NaOH, H 2 O 2 , KMnO 4 , NH 4 NO 3 , H 2 SO 4 , HNO 3 , K 2 SiO 3 , or any combination thereof. 
     
     
         14 . The method of  claim 1 , wherein pyrolyzing the sheet occurs in the presence of N 2 , O 3 , CO 2 , steam, or any combination thereof. 
     
     
         15 . The method of  claim 1 , further comprising:
 using the carbon electrode in a battery, capacitor, supercapacitor, fuel cell, or any combination thereof.   
     
     
         16 . The method of  claim 1 , wherein the carbon electrode and the blank are free of binders. 
     
     
         17 . A carbon electrode comprising:
 a pyrolized sheet of a bio-based material, wherein pyrolized sheet is free of binders, and wherein the pyrolized sheet is an activated carbon.   
     
     
         18 . The electrode of  claim 17 , wherein the sheet has a thickness of less than about 0.6 mm. 
     
     
         19 . The electrode of  claim 17 , wherein the pyrolized sheet is treated with an activation agent, and wherein the activation agent comprises at least one of KOH, ZnCl 2 , H 3 PO 4 , NaOH, H 2 O 2 , KMnO 4 , NH 4 NO 3 , H 2 SO 4 , HNO 3 , K 2 SiO 3 , or any combination thereof. 
     
     
         20 . The electrode of  claim 17 , wherein the pyrolized sheet has a BET surface area of greater than or equal to 1,000 m 2 /g, a tensile strength of greater than or equal to 0.09 N/mm 2 , and a specific capacitance of at least about 50 mF/g.